[RFC PATCH v3 7/8] vfio/type1: Add selective DMA faulting support
Shenming Lu
lushenming at huawei.com
Fri Apr 9 04:44:19 BST 2021
Some devices only allow selective DMA faulting. Similar to the selective
dirty page tracking, the vendor driver can call vfio_pin_pages() to
indicate the non-faultable scope, we add a new struct vfio_range to
record it, then when the IOPF handler receives any page request out
of the scope, we can directly return with an invalid response.
Suggested-by: Kevin Tian <kevin.tian at intel.com>
Signed-off-by: Shenming Lu <lushenming at huawei.com>
---
drivers/vfio/vfio.c | 4 +-
drivers/vfio/vfio_iommu_type1.c | 357 +++++++++++++++++++++++++++++++-
include/linux/vfio.h | 1 +
3 files changed, 358 insertions(+), 4 deletions(-)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 38779e6fd80c..44c8dfabf7de 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2013,7 +2013,8 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
container = group->container;
driver = container->iommu_driver;
if (likely(driver && driver->ops->unpin_pages))
- ret = driver->ops->unpin_pages(container->iommu_data, user_pfn,
+ ret = driver->ops->unpin_pages(container->iommu_data,
+ group->iommu_group, user_pfn,
npage);
else
ret = -ENOTTY;
@@ -2112,6 +2113,7 @@ int vfio_group_unpin_pages(struct vfio_group *group,
driver = container->iommu_driver;
if (likely(driver && driver->ops->unpin_pages))
ret = driver->ops->unpin_pages(container->iommu_data,
+ group->iommu_group,
user_iova_pfn, npage);
else
ret = -ENOTTY;
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index dcc93c3b258c..ba2b5a1cf6e9 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -150,10 +150,19 @@ struct vfio_regions {
static struct rb_root iopf_group_list = RB_ROOT;
static DEFINE_MUTEX(iopf_group_list_lock);
+struct vfio_range {
+ struct rb_node node;
+ dma_addr_t base_iova;
+ size_t span;
+ unsigned int ref_count;
+};
+
struct vfio_iopf_group {
struct rb_node node;
struct iommu_group *iommu_group;
struct vfio_iommu *iommu;
+ struct rb_root pinned_range_list;
+ bool selective_faulting;
};
#define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
@@ -496,6 +505,255 @@ static void vfio_unlink_iopf_group(struct vfio_iopf_group *old)
mutex_unlock(&iopf_group_list_lock);
}
+/*
+ * Helper functions for range list, handle one page at a time.
+ */
+static struct vfio_range *vfio_find_range(struct rb_root *range_list,
+ dma_addr_t iova)
+{
+ struct rb_node *node = range_list->rb_node;
+ struct vfio_range *range;
+
+ while (node) {
+ range = rb_entry(node, struct vfio_range, node);
+
+ if (iova + PAGE_SIZE <= range->base_iova)
+ node = node->rb_left;
+ else if (iova >= range->base_iova + range->span)
+ node = node->rb_right;
+ else
+ return range;
+ }
+
+ return NULL;
+}
+
+/* Do the possible merge adjacent to the input range. */
+static void vfio_merge_range_list(struct rb_root *range_list,
+ struct vfio_range *range)
+{
+ struct rb_node *node_prev = rb_prev(&range->node);
+ struct rb_node *node_next = rb_next(&range->node);
+
+ if (node_next) {
+ struct vfio_range *range_next = rb_entry(node_next,
+ struct vfio_range,
+ node);
+
+ if (range_next->base_iova == (range->base_iova + range->span) &&
+ range_next->ref_count == range->ref_count) {
+ rb_erase(node_next, range_list);
+ range->span += range_next->span;
+ kfree(range_next);
+ }
+ }
+
+ if (node_prev) {
+ struct vfio_range *range_prev = rb_entry(node_prev,
+ struct vfio_range,
+ node);
+
+ if (range->base_iova == (range_prev->base_iova + range_prev->span)
+ && range->ref_count == range_prev->ref_count) {
+ rb_erase(&range->node, range_list);
+ range_prev->span += range->span;
+ kfree(range);
+ }
+ }
+}
+
+static void vfio_link_range(struct rb_root *range_list, struct vfio_range *new)
+{
+ struct rb_node **link, *parent = NULL;
+ struct vfio_range *range;
+
+ link = &range_list->rb_node;
+
+ while (*link) {
+ parent = *link;
+ range = rb_entry(parent, struct vfio_range, node);
+
+ if (new->base_iova < range->base_iova)
+ link = &(*link)->rb_left;
+ else
+ link = &(*link)->rb_right;
+ }
+
+ rb_link_node(&new->node, parent, link);
+ rb_insert_color(&new->node, range_list);
+
+ vfio_merge_range_list(range_list, new);
+}
+
+static int vfio_add_to_range_list(struct rb_root *range_list,
+ dma_addr_t iova)
+{
+ struct vfio_range *range = vfio_find_range(range_list, iova);
+
+ if (range) {
+ struct vfio_range *new_prev, *new_next;
+ size_t span_prev, span_next;
+
+ /* May split the found range into three parts. */
+ span_prev = iova - range->base_iova;
+ span_next = range->span - span_prev - PAGE_SIZE;
+
+ if (span_prev) {
+ new_prev = kzalloc(sizeof(*new_prev), GFP_KERNEL);
+ if (!new_prev)
+ return -ENOMEM;
+
+ new_prev->base_iova = range->base_iova;
+ new_prev->span = span_prev;
+ new_prev->ref_count = range->ref_count;
+ }
+
+ if (span_next) {
+ new_next = kzalloc(sizeof(*new_next), GFP_KERNEL);
+ if (!new_next) {
+ if (span_prev)
+ kfree(new_prev);
+ return -ENOMEM;
+ }
+
+ new_next->base_iova = iova + PAGE_SIZE;
+ new_next->span = span_next;
+ new_next->ref_count = range->ref_count;
+ }
+
+ range->base_iova = iova;
+ range->span = PAGE_SIZE;
+ range->ref_count++;
+ vfio_merge_range_list(range_list, range);
+
+ if (span_prev)
+ vfio_link_range(range_list, new_prev);
+
+ if (span_next)
+ vfio_link_range(range_list, new_next);
+ } else {
+ struct vfio_range *new;
+
+ new = kzalloc(sizeof(*new), GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+
+ new->base_iova = iova;
+ new->span = PAGE_SIZE;
+ new->ref_count = 1;
+
+ vfio_link_range(range_list, new);
+ }
+
+ return 0;
+}
+
+static int vfio_remove_from_range_list(struct rb_root *range_list,
+ dma_addr_t iova)
+{
+ struct vfio_range *range = vfio_find_range(range_list, iova);
+ struct vfio_range *news[3];
+ size_t span_prev, span_in, span_next;
+ int i, num_news;
+
+ if (!range)
+ return 0;
+
+ span_prev = iova - range->base_iova;
+ span_in = range->ref_count > 1 ? PAGE_SIZE : 0;
+ span_next = range->span - span_prev - PAGE_SIZE;
+
+ num_news = (int)!!span_prev + (int)!!span_in + (int)!!span_next;
+ if (!num_news) {
+ rb_erase(&range->node, range_list);
+ kfree(range);
+ return 0;
+ }
+
+ for (i = 0; i < num_news - 1; i++) {
+ news[i] = kzalloc(sizeof(struct vfio_range), GFP_KERNEL);
+ if (!news[i]) {
+ if (i > 0)
+ kfree(news[0]);
+ return -ENOMEM;
+ }
+ }
+ /* Reuse the found range. */
+ news[i] = range;
+
+ i = 0;
+ if (span_prev) {
+ news[i]->base_iova = range->base_iova;
+ news[i]->span = span_prev;
+ news[i++]->ref_count = range->ref_count;
+ }
+ if (span_in) {
+ news[i]->base_iova = iova;
+ news[i]->span = span_in;
+ news[i++]->ref_count = range->ref_count - 1;
+ }
+ if (span_next) {
+ news[i]->base_iova = iova + PAGE_SIZE;
+ news[i]->span = span_next;
+ news[i]->ref_count = range->ref_count;
+ }
+
+ vfio_merge_range_list(range_list, range);
+
+ for (i = 0; i < num_news - 1; i++)
+ vfio_link_range(range_list, news[i]);
+
+ return 0;
+}
+
+static void vfio_range_list_free(struct rb_root *range_list)
+{
+ struct rb_node *n;
+
+ while ((n = rb_first(range_list))) {
+ struct vfio_range *range = rb_entry(n, struct vfio_range, node);
+
+ rb_erase(&range->node, range_list);
+ kfree(range);
+ }
+}
+
+static int vfio_range_list_get_copy(struct vfio_iopf_group *iopf_group,
+ struct rb_root *range_list_copy)
+{
+ struct rb_root *range_list = &iopf_group->pinned_range_list;
+ struct rb_node *n, **link = &range_list_copy->rb_node, *parent = NULL;
+ int ret;
+
+ for (n = rb_first(range_list); n; n = rb_next(n)) {
+ struct vfio_range *range, *range_copy;
+
+ range = rb_entry(n, struct vfio_range, node);
+
+ range_copy = kzalloc(sizeof(*range_copy), GFP_KERNEL);
+ if (!range_copy) {
+ ret = -ENOMEM;
+ goto out_free;
+ }
+
+ range_copy->base_iova = range->base_iova;
+ range_copy->span = range->span;
+ range_copy->ref_count = range->ref_count;
+
+ rb_link_node(&range_copy->node, parent, link);
+ rb_insert_color(&range_copy->node, range_list_copy);
+
+ parent = *link;
+ link = &(*link)->rb_right;
+ }
+
+ return 0;
+
+out_free:
+ vfio_range_list_free(range_list_copy);
+ return ret;
+}
+
static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
{
struct mm_struct *mm;
@@ -910,6 +1168,9 @@ static int vfio_unpin_page_external(struct vfio_dma *dma, dma_addr_t iova,
return unlocked;
}
+static struct vfio_group *find_iommu_group(struct vfio_domain *domain,
+ struct iommu_group *iommu_group);
+
static int vfio_iommu_type1_pin_pages(void *iommu_data,
struct iommu_group *iommu_group,
unsigned long *user_pfn,
@@ -923,6 +1184,8 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
struct vfio_dma *dma;
bool do_accounting;
dma_addr_t iova;
+ struct vfio_iopf_group *iopf_group = NULL;
+ struct rb_root range_list_copy = RB_ROOT;
if (!iommu || !user_pfn || !phys_pfn)
return -EINVAL;
@@ -955,6 +1218,31 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
goto pin_done;
}
+ /*
+ * Some devices only allow selective DMA faulting. Similar to the
+ * selective dirty tracking, the vendor driver can call vfio_pin_pages()
+ * to indicate the non-faultable scope, and we record it to filter
+ * out the invalid page requests in the IOPF handler.
+ */
+ if (iommu->iopf_enabled) {
+ iopf_group = vfio_find_iopf_group(iommu_group);
+ if (iopf_group) {
+ /*
+ * We don't want to work on the original range
+ * list as the list gets modified and in case
+ * of failure we have to retain the original
+ * list. Get a copy here.
+ */
+ ret = vfio_range_list_get_copy(iopf_group,
+ &range_list_copy);
+ if (ret)
+ goto pin_done;
+ } else {
+ WARN_ON(!find_iommu_group(iommu->external_domain,
+ iommu_group));
+ }
+ }
+
/*
* If iommu capable domain exist in the container then all pages are
* already pinned and accounted. Accouting should be done if there is no
@@ -981,6 +1269,15 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
vpfn = vfio_iova_get_vfio_pfn(dma, iova);
if (vpfn) {
phys_pfn[i] = vpfn->pfn;
+ if (iopf_group) {
+ ret = vfio_add_to_range_list(&range_list_copy,
+ iova);
+ if (ret) {
+ vfio_unpin_page_external(dma, iova,
+ do_accounting);
+ goto pin_unwind;
+ }
+ }
continue;
}
@@ -997,6 +1294,15 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
goto pin_unwind;
}
+ if (iopf_group) {
+ ret = vfio_add_to_range_list(&range_list_copy, iova);
+ if (ret) {
+ vfio_unpin_page_external(dma, iova,
+ do_accounting);
+ goto pin_unwind;
+ }
+ }
+
if (iommu->dirty_page_tracking) {
unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
@@ -1010,6 +1316,13 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
}
ret = i;
+ if (iopf_group) {
+ vfio_range_list_free(&iopf_group->pinned_range_list);
+ iopf_group->pinned_range_list.rb_node = range_list_copy.rb_node;
+ if (!iopf_group->selective_faulting)
+ iopf_group->selective_faulting = true;
+ }
+
group = vfio_iommu_find_iommu_group(iommu, iommu_group);
if (!group->pinned_page_dirty_scope) {
group->pinned_page_dirty_scope = true;
@@ -1019,6 +1332,8 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
goto pin_done;
pin_unwind:
+ if (iopf_group)
+ vfio_range_list_free(&range_list_copy);
phys_pfn[i] = 0;
for (j = 0; j < i; j++) {
dma_addr_t iova;
@@ -1034,12 +1349,14 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
}
static int vfio_iommu_type1_unpin_pages(void *iommu_data,
+ struct iommu_group *iommu_group,
unsigned long *user_pfn,
int npage)
{
struct vfio_iommu *iommu = iommu_data;
+ struct vfio_iopf_group *iopf_group = NULL;
bool do_accounting;
- int i;
+ int i, ret;
if (!iommu || !user_pfn)
return -EINVAL;
@@ -1050,6 +1367,13 @@ static int vfio_iommu_type1_unpin_pages(void *iommu_data,
mutex_lock(&iommu->lock);
+ if (iommu->iopf_enabled) {
+ iopf_group = vfio_find_iopf_group(iommu_group);
+ if (!iopf_group)
+ WARN_ON(!find_iommu_group(iommu->external_domain,
+ iommu_group));
+ }
+
do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) ||
iommu->iopf_enabled;
for (i = 0; i < npage; i++) {
@@ -1058,14 +1382,24 @@ static int vfio_iommu_type1_unpin_pages(void *iommu_data,
iova = user_pfn[i] << PAGE_SHIFT;
dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
- if (!dma)
+ if (!dma) {
+ ret = -EINVAL;
goto unpin_exit;
+ }
+
+ if (iopf_group) {
+ ret = vfio_remove_from_range_list(
+ &iopf_group->pinned_range_list, iova);
+ if (ret)
+ goto unpin_exit;
+ }
+
vfio_unpin_page_external(dma, iova, do_accounting);
}
unpin_exit:
mutex_unlock(&iommu->lock);
- return i > npage ? npage : (i > 0 ? i : -EINVAL);
+ return i > npage ? npage : (i > 0 ? i : ret);
}
static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,
@@ -2591,6 +2925,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
iopf_group->iommu_group = iommu_group;
iopf_group->iommu = iommu;
+ iopf_group->pinned_range_list = RB_ROOT;
vfio_link_iopf_group(iopf_group);
}
@@ -2886,6 +3221,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
iopf_group = vfio_find_iopf_group(iommu_group);
if (!WARN_ON(!iopf_group)) {
+ WARN_ON(!RB_EMPTY_ROOT(
+ &iopf_group->pinned_range_list));
vfio_unlink_iopf_group(iopf_group);
kfree(iopf_group);
}
@@ -3482,6 +3819,7 @@ static int vfio_iommu_type1_dma_map_iopf(struct iommu_fault *fault, void *data)
struct vfio_iommu *iommu;
struct vfio_dma *dma;
struct vfio_batch batch;
+ struct vfio_range *range;
dma_addr_t iova = ALIGN_DOWN(fault->prm.addr, PAGE_SIZE);
int access_flags = 0;
size_t premap_len, map_len, mapped_len = 0;
@@ -3506,6 +3844,12 @@ static int vfio_iommu_type1_dma_map_iopf(struct iommu_fault *fault, void *data)
mutex_lock(&iommu->lock);
+ if (iopf_group->selective_faulting) {
+ range = vfio_find_range(&iopf_group->pinned_range_list, iova);
+ if (!range)
+ goto out_invalid;
+ }
+
ret = vfio_find_dma_valid(iommu, iova, PAGE_SIZE, &dma);
if (ret < 0)
goto out_invalid;
@@ -3523,6 +3867,12 @@ static int vfio_iommu_type1_dma_map_iopf(struct iommu_fault *fault, void *data)
premap_len = IOPF_PREMAP_LEN << PAGE_SHIFT;
npages = dma->size >> PAGE_SHIFT;
+ if (iopf_group->selective_faulting) {
+ dma_addr_t range_end = range->base_iova + range->span;
+
+ if (range_end < dma->iova + dma->size)
+ npages = (range_end - dma->iova) >> PAGE_SHIFT;
+ }
map_len = PAGE_SIZE;
for (i = bit_offset + 1; i < npages; i++) {
if (map_len >= premap_len || IOPF_MAPPED_BITMAP_GET(dma, i))
@@ -3647,6 +3997,7 @@ static int vfio_iommu_type1_enable_iopf(struct vfio_iommu *iommu)
iopf_group->iommu_group = g->iommu_group;
iopf_group->iommu = iommu;
+ iopf_group->pinned_range_list = RB_ROOT;
vfio_link_iopf_group(iopf_group);
}
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b7e18bde5aa8..a7b426d579df 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -87,6 +87,7 @@ struct vfio_iommu_driver_ops {
int npage, int prot,
unsigned long *phys_pfn);
int (*unpin_pages)(void *iommu_data,
+ struct iommu_group *group,
unsigned long *user_pfn, int npage);
int (*register_notifier)(void *iommu_data,
unsigned long *events,
--
2.19.1
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